Operating control



April 15, 1952 v G. J. MUcHl-:R 2,593,332

OPERATING CONTROL Filed Nov. 23, 1949 Patented Apr. 15, 1952 OPERATING CONTROL George J. Mucher, Rochester, N. H., assignor to Clarostat Mfg. C0. Inc., Dover, N. H., a corporation of New York Application November 23, 1949, Serial N o. 129,102

4 Claims.

This invention relates to a structurally and functionally improved operating control particularly intended for use in connection with electrical units such as variable resistances and potentiometers.

It is an object of the invention to furnish a control which may be employed where high voltages are encountered and which control will embody a construction as such that there will be no danger of the operator receiving a shock while voperating the control.

A further object is that of furnishing a unit having this advantage and in which the unit oper-- ated by the control, or of which the latter forms its part, may be caused to function with precision and in a positive manner.

An additional object is that of designing an operating control which will involve relatively few parts, each simple and rugged in construction and capable of ready assemblage by quantity production methods to furnish a unitary article operating over long periods of time with freedom from all difficulties.

With these and other objects in mind, reference is had to the attached sheet of drawings illustrating practical embodiments of the invention and in which:

Fig. 1 is a face View of an electrical unit incorporating an improved operating control;

Fig. 2 is a sectional side View of the unit taken along the lines 2-2 and in the direction of the arrows as indicated in Fig." 1

Fig. 3 is a fragmentary sectional side view illustrating one form of shaft coupling which may be employed;

Fig. 4 is a transverse sectional view taken along the lines 4--4 and in the direction of the arrows as indicated in Fig. 3;

Fig. 5 is a view similar to Fig. 3, but showing an alternative form of structure;

Figs. 6 and 7 are fragmentary perspective views of the shaft. as employed in the assemblies illustrated in Figs. 3 and 5, respectively, and

Fig. 3 is a fragmentary sectional view of a preferred assembly.

As is well appreciated by those skilled in the art, various expedients have been resorted to where an instrument such as a. potentiometer has operated under high voltage and in order that the user might not accidentally receive an electric shock. These expedients for the most part have proven quite unsatisfactory. This has either been on the basis of cost, danger of the control failing, or of play coming into existence between the operating end of the shaft and the controlledv part associated with the opposite end of the same.

The present invention overcomes the diiculties heretofore encountered and one form of the same has been shown in Figures 1, 2, 5, and 7 of the accompanying drawings. In those views an operating unit, such as a variable resistance or potentiometer has been shown as including a casing I0 within which a coil-mounting strip II is suitably disposed. The convolutions of the coil are traversed by a contact member I2 which may also function as a stop and the assembly may be mounted conveniently by having a screwthreaded collar I3 extending from casing I0 and upon the threads of which nuts I4 are disposed. These nuts may clamp between them the opposite surfaces of a support (not shown). A shaft I6 may extend from within the casing I0 to a point exteriorly of a dielectric panel I5. This shaft is conveniently formed with a groove I 1 within which a split ring I8 may extend to retain the shaft against axial displacement.

It will be understood that the views in Figs. 1 and 2 are merely illustrative of one form of control and are more or less conventional. The controlled unit or instrument might embody numerous different forms of construction and include a greater or lesser number of parts. It is quite immaterial for a consideration of the present invention, whether the operating shaft extends through a panel disposed as indicated at l5 in Fig. 2; the problem solved by the present teachings being those of guarding a person turning the outer end of that shaft from receiving anV electric shock and preventing relative movement between the several parts of the assembly.

With this in mind the shaft is of dielectric material and is conveniently manufactured of plastic. Its end as especially shown in Fig. 'l is milled or otherwise formed to provide an extension I9 of non-circular configuration. This extension is bored as at 20 so as to be capable of receiving a 'screw 2I of the type shown in Fig. 5.

The contact assembly may include a ringshaped plate 22 formed with an integral contact extension 23, a plate 24 of insulating material and a metallic contact element 25. Both the latter and plate 24 are formed with openings through which the projection I9 may extend and these openings are likewise non-circular in outline and conform to the outline of the extension so that relative rotation of these parts will be prevented. The plate 24 of insulating material maybe formed with notches 26 into which arms or extensions 21 of the ring 22 project. These 3 extensions are bent over as shown in Figs. 1 and 2; it being thus obvious that relative rotation between the ring 22 and plate 24 is prevented.

Plate 24 may also be formed with a relatively extended or supporting portion 28 conveniently underlying and bracing the extended portion 29 presenting the contact I2. .Member 25 is also preferably formed with inturned extensions 3|) lying one to each side of the extension 2B and disposed adjacent to the side edges of the latter.

Thus, it is apparent that due to the non-circular configuration of extension I9 and the corresponding outline of the openings in plate 24 and member 25 which receive that extension, relative rotation of the parts is prevented. Also, the ring 22 having its arms or clips 21 extending into the notches 26 of plate 24, it follows that the ring will be fixed against rotation with respect to that plate. Moreover, the parts will turn as a unit With shaft I6, because of the bracing and support occurring between side edges of the extension 2-8 and 30 which will preclude a rotation of member 25 with respect to the insulating plate. With the parts thus positioned, it is apparent that by simply driving the screw 2| into socket 20 and with the head of the screw overlying the outer face of member 25, axial displacement of the assembly with respect to the shaft will also be prevented.

It will be understood in the case of shaft I6 being formed of certain plastics, it might be desirable to heat or treat in a number of different manners, the end of the shaft which receives the screw 2| at the time the latter is forced to a seated position. Ordinarily, this will not be necessary, however, and by simply using pressure the parts may be properly secured. If it is not desired to use a screw 2|, a spring washer or nut may be employed. This has been illustrated in Figs. 3, 4 and 6.

In those views, the numeral I6 again indicates the shaft of dielectric material formed with an extension I9 of irregular configuration. Mounted upon this extension is an insulating plate 24, carrying ring 22; a contact member 25 being likewise disposed upon the extension. However, instead of forming the extension with a bore 20, a projecting portion 3| in the form of a mounting-hub is provided beyond the extension. With the contact assembly positioned upon the shaft, this hub simply receives and supports a spring nut or washer 32. As this element is forced home, it bites into the material of the hub 3|, thus preventing accidental displacement of the washer and firmly retainin the parts in position.v v

In both forms herein illustrated, it will be understood that an operator grasping the outer end of shaft I6 may freely rotate the same by, for example, a knob (not shown) without any danger of receiving a shock. At the same time,

it will be apparent that in such rotation no play Will occur between the contact assembly and the shaft and such as' would interfere with the operation of the instrument or unit. In other words, the operator, in rotating the shaft, will have absolute assurance that the contact assembly is being similarly moved without anyeffective lag. At the same time, it will not have been necessary to resort to expensive and complicated couplings. There isprovided rather a simple and economical assembly, the parts of which may be produced by quantity manufacturing methods. Addition- 4 ally, parts may be readily assembled by relatively unskilled labor.

The same is true of the structure shown in Fig. 8. In that view the numeral I6 again indicates the shaft of dielectric material which, similarly to the structure shown in Fig. 7 is formed with a recess. This recess accommodates the splined end of a mounting and retaining member 33 which is formed with a groove 34 and a reduced outer end portion. Upon the latter an assembly is mounted which may include a ring member 35, a plate 36 of insulating material and a contact unit 37. Relative rotation between these parts is prevented as, for example, in the manner shown in Figs. 1, 4, etc. and ring 35 may also be turned inwardly as at 38 to engage plate 36 and thus assure this result. After the parts are disposed in proper relationship, the end of member 33 is headed as at 39. In this connection it will be understood that any damage to the assembly incident to the heading operation is prevented because gripping and supporting jaws (not shown) may extend into groove 34 and engage the surfaces of member 33. Accordingly all supporting strains Will be confined to that member rather than being transmitted to the shaft I6 with danger of breakage to the latter.

Thus, among others, the several objects of the invention as specifically aforenoted are achieved. Obviously, numerous changes in construction and rearrangement of the parts might be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

1. An operating control including in combination means providing a current-conducting area, a contact member movably mounted to engage and pass over said area, a rotatable shaft of di-l electric material, an extension forming a part of said shaft, said extension being of non-circular outline and passing through a correspondingly shaped opening in said member, said shaft being formed with a bore extending through to the face of said extension and a headed screw having its shank extending within said bore, its head overv lying said member to retain the latter.

2. An operating control including in combination means providing a current-conductingiarea, a contact member movably mounted to engage and pass over said area, a rotatable shaft of dielectric material, an extension forming a part of said shaft,y said extension being of non-circular outline and passing through a correspondingly shaped opening in said member, a projecting portion forming apart of said shaft beyond said ex- 1 tension and a spring-type nut mounted upon said projection and bearing against said member to retain the latter against displacement.

3. An operating control for electrical instruments, said control including an rotatable shaft ofY said recess and beyond said shaft', saidm'i'n'ber 5 presentinggin outer end portion to receive a, contact assembly and said member at a point short of said ou i"l end being formed with a. tool-accommodminzfgfy recess whereby said member may vbe supportdwhile its outer end is headed.

GEORGE J. MUCHER.

REFERENCES CITED The folld'ing references are of record in the le of this'iiatent:

Number UNITED STATES PATENTS Name Date Bond May 5, 1931 Schellenger Dec. 31, 1935 Mucher Jan. 13, 1948 FOREIGN PATENTS Country Date Great Britain Feb. 29, 1944 France 1 Apr. 27, 1939 

